use ddc::Ddc;
use ddc_i2c::{I2cDeviceDdc, I2cDeviceEnumerator};
use rosc;
use rumqttc::mqttbytes::v4::Packet;
use rumqttc::{Client, Event, MqttOptions, QoS};
use std::collections::HashMap;
use std::env;
use std::error::Error;
use std::net::UdpSocket;
use std::sync::mpsc::{channel, Receiver, Sender};
use std::thread;
use std::time::{Duration, Instant};
use tracing::{event, Level};

pub type StdError<T> = Result<T, Box<dyn Error>>;

enum Command {
    Monitor((usize, MonitorCommand)),
}

enum MonitorCommand {
    Brightness(u8),
    Input(u8),
}

impl MonitorCommand {
    fn cmd_str(&self) -> &'static str {
        match self {
            Self::Brightness(_) => "brightness",
            Self::Input(_) => "input",
        }
    }

    fn vcp(&self) -> u8 {
        match self {
            Self::Brightness(_) => 0x10,
            Self::Input(_) => 0x60,
        }
    }
}

// Run an i2c command handler for a specific i2c device, rate limiting each type of command
fn run_i2c(mut dev: I2cDeviceDdc, command_channel: Receiver<MonitorCommand>) {
    let mut last_sent_command: HashMap<&str, Option<Instant>> = HashMap::new();
    loop {
        let cmd = command_channel.recv().unwrap();
        if let Some(last) = last_sent_command.entry(cmd.cmd_str()).or_insert(None) {
            if (*last + Duration::from_millis(100)) > Instant::now() {
                // rate limit
                continue;
            }
        }
        match cmd {
            MonitorCommand::Brightness(b) => dev.set_vcp_feature(cmd.vcp(), b.into()).unwrap(),
            // Hack - add 15 to align with DELL monitors
            MonitorCommand::Input(i) => dev.set_vcp_feature(cmd.vcp(), (i + 15).into()).unwrap(),
        }
        last_sent_command.insert(cmd.cmd_str(), Some(Instant::now()));
    }
}

pub fn main() -> StdError<()> {
    let displays = I2cDeviceEnumerator::new().unwrap().collect::<Vec<_>>();
    println!("Enumerated {} displays", displays.len());
    let txes: Vec<_> = displays
        .into_iter()
        .map(|d| {
            let (tx, rx) = channel();
            thread::spawn(move || run_i2c(d, rx));
            tx
        })
        .collect();
    run_mqtt(&txes)?;
    Ok(())
}

fn run_mqtt(txes: &Vec<Sender<MonitorCommand>>) -> StdError<()> {
    let client_id = env::var("MQTT_CLIENT_ID").unwrap_or("ddcmqtt".into());
    let mqtt_host = env::var("MQTT_HOST").unwrap_or("localhost".into());
    let mqtt_port = env::var("MQTT_PORT")
        .unwrap_or("1883".into())
        .parse::<u16>()?;
    let mqtt_user = env::var("MQTT_USER").ok();
    let mqtt_pass = env::var("MQTT_PASS").ok();
    let mut mqttoptions = MqttOptions::new(client_id, mqtt_host.clone(), mqtt_port);
    // Set credentials if we have user and pass specified.
    // TODO: warn if only one maybe?
    if let (Some(u), Some(p)) = (mqtt_user, mqtt_pass) {
        event!(Level::INFO, user = u, "Using MQTT user/pass from env");
        mqttoptions.set_credentials(u, p);
    }
    mqttoptions.set_keep_alive(Duration::from_secs(5));

    let (mut client, mut connection) = Client::new(mqttoptions, 10);
    client.subscribe("ddcmqtt/#", QoS::AtMostOnce)?;

    event!(Level::INFO, mqtt_host, mqtt_port, "Running MQTT client");

    for notification in connection.iter() {
        event!(Level::INFO, ?notification, "Got notification");
        if let Ok(Event::Incoming(Packet::Publish(p))) = notification {
            let topic: Vec<_> = p.topic.split("/").collect();
            if topic.len() != 3 {
                event!(
                    Level::WARN,
                    ?topic,
                    "Publish topic has wrong format, ignoring."
                );
                continue;
            }
            if topic[0] != "ddcmqtt" {
                event!(
                    Level::ERROR,
                    ?topic,
                    "Got publish that we didn't subscribe to!"
                );
                continue;
            }
            let mon_idx = topic[1].parse::<u8>();
            match (mon_idx, topic[2]) {
                (Ok(idx), "input") => {
                    // TODO: don't crash on these ?s - I'm feeling lazy
                    let input_id = std::str::from_utf8(&p.payload)?.parse::<u8>()?;
                    handle_cmd(
                        Command::Monitor((idx.into(), MonitorCommand::Input(input_id))),
                        &txes,
                    )?;
                }
                _ => {
                    event!(Level::ERROR, ?topic, "Unrecognised or invalid topic");
                    continue;
                }
            }
        }
    }
    Ok(())
}

fn run_osc(txes: &Vec<Sender<MonitorCommand>>) -> StdError<()> {
    let sock = UdpSocket::bind("0.0.0.0:1234")?;
    let mut buf = [0u8; rosc::decoder::MTU];

    loop {
        let (size, addr) = sock.recv_from(&mut buf).unwrap();
        println!("Got {} bytes from {}", size, addr);
        let (_, pack) = rosc::decoder::decode_udp(&buf[..size]).unwrap();
        match pack {
            rosc::OscPacket::Message(msg) => {
                match osc_message_to_command(msg) {
                    Ok(cmd) => {
                        if let Err(e) = handle_cmd(cmd, &txes) {
                            println!("Error handling command: {:?}", e);
                        }
                    }
                    Err(e) => println!("Unrecognised OSC command: {:?}", e),
                };
            }
            rosc::OscPacket::Bundle(bundle) => {
                println!("OSC Bundle: {:?}", bundle);
            }
        }
    }
}

fn handle_cmd(cmd: Command, txes: &Vec<Sender<MonitorCommand>>) -> StdError<()> {
    match cmd {
        Command::Monitor((idx, c)) => txes.get(idx).ok_or("Bad monitor index")?.send(c)?,
    };
    Ok(())
}

fn osc_message_to_command(msg: rosc::OscMessage) -> StdError<Command> {
    println!("OSC: {}, args: {:?}", msg.addr, msg.args);
    let splitaddr: Vec<_> = msg.addr.split("/").collect();
    match &splitaddr[1..] {
        ["monitor", idx, control] => {
            println!("Monitor {}, control {}, args {:?}", idx, control, msg.args);
            let command = match *control {
                "brightness" => Some(MonitorCommand::Brightness(
                    (msg.args[0].clone().float().unwrap() * 100.0) as u8,
                )),
                "input" => Some(MonitorCommand::Input(
                    (msg.args[0].clone().int().unwrap()) as u8,
                )),
                _ => None,
            }
            .ok_or(format!("Unrecognised monitor control: {}", *control))?;
            let idx = idx.parse::<usize>().or(Err("Bad monitor index"))?;
            Ok(Command::Monitor((idx, command)))
        }
        _ => Err("Unsupported osc address, ignoring".into()),
    }
}